The present invention relates to a method for controlling the wort flow from a lauter tun and a device for performing such a method.
A method for controlling wort outflow during brewing is, for instance, known from the European patent application EP-A-0362 793. In this method, the wort outflow quantity is measured and compared with a predeterminable outflow value. This outflow value serves as a set value, the actually measured wort outflow quantity serving as an actual value. The raking machine which is arranged within the lauter tun is lifted or lowered in response to the difference between the actual value and the set value. When the flow rate of the wort decreases, the raking device is moved into a lower position to loosen the grain bed which has settled on, the false bottom of the lauter tun. The resistance of the grain bed is reduced by the loosening operation, so that the wort flow rate can be increased. The time needed for lautering the wort on the whole can be reduced. There may also be set different outflow values in different phases so as to be able to work with corresponding suitable outflow values in the individual sections (first wort recovery, second worts).
Although the lauter time can be reduced with this method, the lauter process remains, in the present method, that process in wort production that requires most of the time and should therefore be further reduced with a view to a further increase in the brew sequence, i.e., without impairment to the wort quality. Furthermore, it is desirable to have possibilities of individual adaptation for the most different types of beer, raw material compositions, grist compositions, mash consistencies and loads on the lauter tuns.
It is therefore the object of the present invention to further shorten the time for lautering the wort in a method and in a device of the above-mentioned type, with such a shortening being possible under the most different conditions and with the most different types of beer, raw material compositions, etc.
This object is achieved according to the invention in that in the course of the total sequence of a brew process (first wort, second worts) a second increased outflow value which is to be reached within a specific time interval is predetermined in at least one phase (trending phase), based on the predetermined outflow value of the wort outflow, that the increase in flow rate/per time unit (increase value) as required for reaching the second outflow value is determined on the basis of these values, and that this determined increase value is used as a set value for controlling an outflow regulator.
Hence, at least one phase, which may be designated as trending, is included in this invention in a complete lauter process which ranges from the first wort recovery to the second worts. In this phase, the wort outflow quantity is not regulated to have a constant wort outflow value, but is regulated on the basis of a rising, especially staircase-like outflow curve which is determined in that, by setting a specific increased outflow quantity which is to be reached after a certain time, the resultant rise is calculated for the increase in flow rate per time unit (set value).
The outflow quantity can be varied by regulating the effective flow opening of a regulating valve, or by regulation via the opening angle of a lauter flap.
In a very advantageous embodiment of the invention, the raking machine provided within the lauter tun is included in or combined with the control loop for controlling the outflow quantity according to EP-A-0326 793.
This may advantageously be done in that, when a specific stepwise increase in the opening angle of the lauter flap by a specific angular amount (e.g. 8%) does not yield a corresponding increase in-the flow rate during the trending phase, the raking machine is slightly lowered to effect an increase in the outflowing wort amount.
This trending phase may be carried out until the second increased outflow value has been reached or until the flap position has reached a limit value which is also predeterminable (e.g. 80% total opening angle), so that a further increase no longer yields a significant increase in flow rate.
It is advantageous in the course of the trending phase when the set value can be varied. In particular, the set value is reduced if an increased flow rate of the wort cannot be reached, whereby the grain bed is prevented from getting stuck or from solidifying. This would lead to a deep cut which is not desired in the trending phase. As soon as the flow rate of the wort has stabilized over a certain period of time, the increase in the flow rate per time unit is continued with the original set value.
In a lauter tun of the type as described at the outset, the device for performing the method provides for an outflow regulator which is connected to the control means for regulating the amount of the outflowing wort.
This measure makes it possible to perform the method, since the outflow regulator can then be included in the control loop and can automatically be influenced by the control means in accordance with the respectively desired values.